Abstract: Empty fruit bunches EFB are treated with distilled water at different washing medium temperature. The effects on the yield distribution of pyrolysis products and its particulate emission released are studied via feedstock behaviours analysis and the effectiveness of washing pre-treatment. Room temperature washing medium is considered as the optimum washing medium condition of pre-treatment in order to provide better qualities of feedstock for pyrolysis work. The feedstock are possessed with minimal weight percentage of ash content, and acquired great amount of volatiles matter and energy value of 87.63 wt% and 18.04 MJ-kg, respectively. Furthermore, yield distribution of EFB pyrolysis products are enhanced to around 40.98 wt% of bio-char, 55.08 wt% of pyrolysis liquid and 3.93 wt% of gas. Particulate emissions of EFB feedstock are described accordingly by three combustion phases of pyrolysis process. The raw-untreated EFB was revealed to release higher amount of particulate emission along the pyrolysis activity as compared to the treated EFB feedstock. The papers primary contribution is finding that the properties of empty fruit bunches are improved by the employment of water washing pre-treatment. Better feedstock behaviours will promoting positive influence towards the yield distribution of pyrolysis products at minimal release of the particulate emission during burning activity.